There was a fascinating news article last Thursday on how culture affects the reading of emoticons between the Japanese and the Americans. Because Americans focus more on the mouth when attempting to read facial expressions, our emoticons have also evolved this way, :) for example, the parenthesis representing a smiling mouth. The Japanese, on the other hand, rarely use exaggerated expressions when emoting, so culturally, they focus on a subject's eyes when reading expressions. Consequently, their emoticons have evolved to emphasize the eyes, ^_^ where the carrots are smiling eyes. If you've ever been on an anime forum, you would see a whole range of these asian style emoticons.
Then, of course, there's the whole subgenre of lolcaticons. I wonder what the study would have to say about them: